Ahwell, do we know for sure you can claim the free game as one you've used to register? Seeing as I'm considering buying Fire Emblem anyway.
I read it somewhere on the Nintendo website that you can download any one of the 8 games as long as you've registered 3 of them. It doesn't mention anywhere that the one you download for free can't be one you registered.
Plus it's probably in Nintendo's financial interest that you download one you have already registered anyway. As technically, they're not giving away a game that way as it's already been paid for...